Method and apparatus for chip-cooling

Abstract

A thermal interface for IC chip cooling is provided. One embodiment of the thermal interface includes a thermally conductive liquid or paste-like metal(s) disposed within a flexible, thermally conductive enclosure. The enclosure is adapted to be placed between an IC chip and a heat sink to enhance heat transfer from the chip to the heat sink, thereby enabling quicker and more efficient cooling of the chip than can be achieved by conventional techniques. In several embodiments, the thermal interface is held in place by mechanical pressure rather than by bonding, which further facilitates inspection and repair of the IC device.

1. A thermal interface comprising:
 a thermally conductive fluid; 
 a flexible enclosure for confining the thermally conductive fluid; and 
 at least one containment pad surrounding a perimeter edge of the enclosure. 
 
   
   
     2. The thermal interface of  claim 1 , further comprising:
 a flexible liner lining an interior surface of the enclosure. 
 
   
   
     3. The thermal interface of  claim 2 , wherein the liner is formed from a chemically inert metal. 
   
   
     4. The thermal interface of  claim 1 , wherein the at least one containment pad comprises:
 an indentation sized and positioned to receive the perimeter edge of the enclosure, for sealing the thermal interface against an outside environment. 
 
   
   
     5. The thermal interface of  claim 1 , wherein the thermally conductive fluid is a liquid metal. 
   
   
     6. The thermal interface of  claim 5 , wherein the liquid metal is selected from a group consisting of gallium, mercury, gallium-indium and mercury-gold. 
   
   
     7. The thermal interlace of  claim 1 , wherein the enclosure comprises:
 at least one flexible metal foil. 
 
   
   
     8. The thermal interface of  claim 7 , wherein the at least one flexible metal foil is selected from a group consisting of copper, aluminum, stainless steel, nickel and silicon. 
   
   
     9. The thermal interface of  claim 7 , wherein the enclosure comprises:
 two flexible foils sealed together around a perimeter edge to form a cavity therebetween. 
 
   
   
     10. The thermal interface of  claim 7 , wherein the enclosure comprises:
 a single flexible foil folded over and sealed around a perimeter edge to create a pocket. 
 
   
   
     11. An integrated circuit device comprising:
 at least one heat source; 
 at least one heat sink positioned in proximity to the at least one heat source; and 
 at least one thermal interface positioned between the at least one heat source and the at least one heat sink, the thermal interface comprising:
 a thermally conductive fluid; 
 an enclosure for confining the thermally conductive fluid, wherein at least one surface of the enclosure is flexible and the enclosure is in thermal contact with both the at least one heat source and the at least one heat sink; and 
 at least one flexible gasket sealing a perimeter around the at least one heat source and the at least one heat sink. 
 
 
   
   
     12. The integrated circuit device of  claim 11 , wherein the at least one thermal interface further comprises:
 a flexible liner lining an interior surface of the enclosure. 
 
   
   
     13. The integrated circuit device of  claim 12 , wherein the liner is formed from a chemically inert metal. 
   
   
     14. The integrated circuit device of  claim 11 , further comprising:
 at least one optimization layer disposed between the at least one thermal interface and the at least one heat source, between the at least one thermal interface and the at least one heat sink, or both, the optimization layer comprising a material selected from the group consisting of water, epoxy, oil, paste, solder, organic fluid and liquid metal. 
 
   
   
     15. The integrated circuit device of  claim 11 , wherein the thermally conductive fluid is a liquid metal. 
   
   
     16. The integrated circuit device of  claim 11 , wherein the enclosure comprises:
 at least one flexible metal foil. 
 
   
   
     17. The integrated circuit device of  claim 16 , wherein the enclosure comprises:
 two flexible foils sealed together around a perimeter edge to form a cavity therebetween. 
 
   
   
     18. The integrated circuit device of  claim 16 , wherein the enclosure comprises:
 a single flexible foil folded over and sealed around a perimeter edge to create a pocket. 
 
   
   
     19. The integrated circuit device of  claim 16 , wherein the enclosure comprises a single metal foil sealed around its perimeter edge to a surface of the at least one heat sink. 
   
   
     20. The integrated circuit device of  claim 11 , wherein the at least one thermal interface comprises a plurality of thermal interfaces arranged in the form of an interposer. 
   
   
     21. An integrated circuit device comprising:
 at least one heat source; 
 at least one heat sink positioned in proximity to the at least one heat source; and 
 at least one thermal interface positioned between the at least one heat source and the at least one heat sink, the thermal interface comprising:
 a thermally conductive fluid retained between the at least one heat source and the at least one heat sink; and 
 at least one flexible gasket sealing a perimeter around the at least one heat source and the at least one heat sink, for retaining the fluid therebetween. 
 
 
   
   
     22. Method for facilitating heat transfer from a heat source to a heat sink, the method comprising the steps of:
 providing a thermally conductive fluid between the heat source and the heat sink, said thermally conductive fluid being in thermal contact with both the heat source and the heat sink; and 
 enclosing the thermally conductive fluid in a thermally conductive enclosure, wherein at least a portion of the enclosure is flexible, and wherein the step of enclosing the thermally conductive fluid comprises enclosing the fluid in a cavity formed between the heat source and the heat sink, the cavity being sealed around a perimeter by a flexible gasket. 
 
   
   
     23. The method of  claim 22 , wherein the step of enclosing the thermally conductive fluid comprises enclosing the fluid in a cavity formed between two flexible foils. 
   
   
     24. The method of  claim 22 , wherein the step of enclosing the thermally conductive fluid comprises enclosing the fluid in a cavity formed between a flexible foil and the heat sink, the flexible foil being sealed to the heat sink around a perimeter edge. 
   
   
     25. Method for assembling a multi-chip integrated circuit device comprising the steps of:
 assembling two or more integrated circuit chips on a substrate; 
 placing a thermal interface in contact with each of the two or more integrated circuit chips, the thermal interface comprising:
 a thermally conductive fluid; 
 a flexible enclosure for confining the thermally conductive fluid; and 
 at least one containment pad surrounding a perimeter edge of the enclosure; and 
 
 placing a heat sink in thermal contact each of the two or more integrated circuit chips. 
 
   
   
     26. An integrated circuit device comprising:
 at least one heat source; 
 at least one heat sink positioned in proximity to the at least one heat source; and 
 at least one thermal interface positioned between the at least one heat source and the at least one heat sink, the thermal interface comprising:
 a thermally conductive fluid; 
 an enclosure for confining the thermally conductive fluid, wherein at least one surface of the enclosure is flexible and the enclosure is in thermal contact with both the at least one heat source and the at least one heat sink; and 
 at feast one containment pad surrounding a perimeter edge of the enclosure. 
 
 
   
   
     27. The integrated circuit device of  claim 26 , wherein the at least one containment pad comprises:
 an indentation sized and positioned to receive the perimeter edge of the enclosure, for sealing the at least one thermal interface against an outside environment.